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133
main.tex
133
main.tex
@@ -94,7 +94,7 @@ has simply been esterified differently than ASA.\\
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\label{fig:methyl-salicylate}
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\end{figure}
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Due to the similarity between the two molecules, ASA can be reacted to synthesize methyl salicylate~\cite{Hartel2009}.
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Due to the similarity between the two molecules, ASA can be reacted to synthesize methyl salicylate~\cite{Hartel2009,nilered2017aspirin}.
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The purpose of this experiment was to convert acetylsalicylic acid obtained from
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commercial aspirin tablets into methyl salicylate through acid-catalyzed esterification
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in methanol under reflux conditions.
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@@ -173,6 +173,33 @@ The transformation encompasses two concurrent equilibrium-driven processes:
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To drive the reaction toward the methyl salicylate product, a substantial stoichiometric excess of methanol was employed, utilizing Le Chatelier's principle to overcome the reversible nature of the esterification.
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\subsection{Kinetic and Thermodynamic Analysis}
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The transformation efficiency of the tandem hydrolysis--esterification is determined by the interplay between reaction rate and equilibrium position.
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\subsubsection{Thermal Activation and Collision Theory}
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The reflux duration is required to provide the activation energy ($E_{a}$) necessary for the nucleophilic attack on the sterically hindered aryl ester. According to the Arrhenius relationship, the rate constant $k$ increases exponentially with temperature:
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\begin{equation}
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k = Ae^{-E_{a}/RT}
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\end{equation}
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Operating at the boiling point of the solvent increases the frequency of effective collisions and facilitates the formation of the required carbocation intermediates.
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Furthermore, by employing a vast molar excess of methanol, the system effectively follows pseudo-first-order kinetics. Under these conditions, the concentration of the alcohol remains negligible in its variation, and the rate depends solely on the concentration of the limiting aspirin precursor:
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\begin{equation}
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-\frac{d[\text{ASA}]}{dt} = k'[\text{ASA}] \implies [\text{ASA}]_{t} = [\text{ASA}]_{0}e^{-k't}
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\end{equation}
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\subsubsection{Equilibrium Shifts and Chemical Potential}
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As a reversible process, the yield is limited by the equilibrium constant ($K$). Because the esterification step is endothermic ($\Delta H^\circ > 0$), the application of heat shifts the equilibrium toward the products. This temperature dependence is quantified by the Van't Hoff equation:
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\begin{equation}
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\frac{d \ln K}{dT} = \frac{\Delta H^\circ}{RT^{2}}
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\end{equation}
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The high reactant-to-substrate ratio further ensures that the reaction quotient ($Q$) remains lower than $K$ throughout the process. This maintains a negative Gibbs free energy ($\Delta G$), driving the reaction toward the formation of methyl salicylate:
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\begin{equation}
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\Delta G = \Delta G^\circ + RT \ln Q
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\end{equation}
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The combination of thermal input and stoichiometric bias effectively overcomes the reversible nature of the Fischer esterification.
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\subsection{Work-up and Purification}
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Following reflux, the reaction was quenched in ice-cold distilled water. Methyl salicylate ($\rho \approx 1.17$ g/mL) was isolated as the organic phase via liquid--liquid extraction. Residual acidic species (\ce{H2SO4}, \ce{CH3COOH}) were neutralized using saturated \ce{NaHCO3}:
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@@ -183,113 +210,9 @@ Following reflux, the reaction was quenched in ice-cold distilled water. Methyl
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The organic extract was dried over anhydrous \ce{MgSO4} and filtered to yield the pure essential oil.
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\subsection{Outline}
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The document layout should follow the style of the journal concerned. Where
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appropriate, sections and subsections should be added in the normal way.
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\subsection{References}
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References should be given in the normal way in \LaTeX{}. If you are using
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\textsf{biblatex} (as recommended) then you can use the full range of citation
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commands it provides. If you choose to use classical Bib\TeX{}, the
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\textsf{natbib} package will be loaded and you can use it's commands.
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\subsection{Floats}
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New float types are set up in the preamble. The means graphics are included as
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follows (Scheme~\ref{sch:example}). As illustrated, the float is ``here'' if
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possible.
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\begin{scheme}
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\centering
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Your scheme graphic would go here: PDF graphics are recommended.
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%\includegraphics{graphic}
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\caption{An example scheme}
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\label{sch:example}
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\end{scheme}
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The use of the different floating environments is not required, but it is
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intended to make document preparation easier for authors. In general, you
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should place your graphics where they make logical sense; the production
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process will move them if needed.
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\subsection{Math}
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If packages such as \textsf{amsmath} are required, they should be loaded in the
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preamble. However, the basic \LaTeX\ math(s) input should work correctly
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without this. Some inline material $1 + 1 = 2$ followed by some display. \[ A =
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\pi r^2 \]
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It is possible to label equations in the usual way (Eq.~\ref{eqn:example}).
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\begin{equation}
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\frac{\mathrm{d}}{\mathrm{d}x} \, r^2 = 2r \label{eqn:example}
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\end{equation}
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This can also be used to have equations containing graphical content. To align
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the equation number with the middle of the graphic, rather than the bottom, a
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minipage may be used.
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\begin{equation}
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\begin{minipage}[c]{0.80\linewidth}
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\centering
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As illustrated here, the width of \\
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the minipage needs to allow some \\
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space for the number to fit in to.
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%\includegraphics{graphic}
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\end{minipage}
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\label{eqn:graphic}
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\end{equation}
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\section{Experimental}
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The usual experimental details should appear here. This could include a table,
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which can be referenced as Table~\ref{tbl:example}. Notice that the caption is
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positioned at the top of the table.
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\begin{table}
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\caption{An example table}
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\label{tbl:example}
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\centering
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\begin{tabular}{ll}
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\hline
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Header one & Header two \\
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\hline
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Entry one & Entry two \\
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Entry three & Entry four \\
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Entry five & Entry five \\
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Entry seven & Entry eight \\
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\hline
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\end{tabular}
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\end{table}
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Adding notes to tables can be complicated. Perhaps the easiest method is to
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generate these using the basic \texttt{\textbackslash textsuperscript} and
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\texttt{\textbackslash emph} macros, as illustrated (Table~\ref{tbl:notes}).
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\begin{table}
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\caption{A table with notes}
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\label{tbl:notes}
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\centering
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\begin{tabular}{ll}
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\hline
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Header one & Header two \\
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\hline
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Entry one\textsuperscript{\emph{a}} & Entry two \\
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Entry three\textsuperscript{\emph{b}} & Entry four \\
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\hline
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\end{tabular}
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\textsuperscript{\emph{a}} Some text;
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\textsuperscript{\emph{b}} Some more text.
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\end{table}
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The example file also loads the optional \textsf{chemformula} and
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\textsf{mhchem} packages, so that formulas are easy to input:
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\texttt{\textbackslash ce\{H2SO4\}} gives \ce{H2SO4}. The two have similar
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syntax but authors may prefer one or the other.
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The use of new commands should be limited to simple things which will not
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interfere with the production process. For example, \texttt{\textbackslash
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mycommand} has been defined in this example, to give italic, mono-spaced text:
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\mycommand{some text}.
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\section*{Acknowledgements}
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@@ -55,3 +55,14 @@
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month = Apr,
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pages = {475}
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}
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@online{nilered2017aspirin,
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author = {NileRed},
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title = {Turning aspirin pills into mint flavor},
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year = {2017},
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month = jul,
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day = {17},
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organization = {YouTube},
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url = {https://www.youtube.com/watch?v=3NN9IUvrKi4},
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note = {YouTube video, 10.7M subscribers, 2,057,102 views, accessed 2026-05-12}
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}
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